Delivery systems and methods of implantation for prosthetic heart valves

ABSTRACT

A delivery system for delivering an implantable stented device to a lumen of a patient, the delivery system including an elongated body having a proximal end and a distal end, a driver mechanism positioned at the proximal end of the elongated body, an elongated threaded rod located axially distal to the driver mechanism, and a sheath including an elongated tubular portion having a hollow interior portion with a first diameter that is sized for compression and retention of the implantable stented device in a compressed configuration for delivery to a body lumen.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional ApplicationNo. 61/062,207, filed Jan. 24, 2008, and titled “Delivery Systems andMethods of Implantation for Prosthetic Heart Valves”, the entirecontents of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to prosthetic heart valves. Moreparticularly, it relates to devices, methods, and delivery systems forpercutaneously implanting prosthetic heart valves.

BACKGROUND

Diseased or otherwise deficient heart valves can be repaired or replacedusing a variety of different types of heart valve surgeries. Typicalheart valve surgeries involve an open-heart surgical procedure that isconducted under general anesthesia, during which the heart is stoppedwhile blood flow is controlled by a heart-lung bypass machine. This typeof valve surgery is highly invasive and exposes the patient to a numberof potentially serious risks, such as infection, stroke, renal failure,and adverse effects associated with use of the heart-lung machine, forexample.

Recently, there has been increasing interest in minimally invasive andpercutaneous replacement of cardiac valves. Such surgical techniquesinvolve making a very small opening in the skin of the patient intowhich a valve assembly is inserted in the body and delivered to theheart via a delivery device similar to a catheter. This technique isoften preferable to more invasive forms of surgery, such as theopen-heart surgical procedure described above. In the context ofpulmonary valve replacement, U.S. Patent Application Publication Nos.2003/0199971 A1 and 2003/0199963 A1, both filed by Tower, et al.,describe a valved segment of bovine jugular vein, mounted within anexpandable stent, for use as a replacement pulmonary valve. Thereplacement valve is mounted on a balloon catheter and deliveredpercutaneously via the vascular system to the location of the failedpulmonary valve and expanded by the balloon to compress the valveleaflets against the right ventricular outflow tract, anchoring andsealing the replacement valve. As described in the articles:“Percutaneous Insertion of the Pulmonary Valve”, Bonhoeffer, et al.,Journal of the American College of Cardiology 2002; 39: 1664-1669 and“Transcatheter Replacement of a Bovine Valve in Pulmonary Position”,Bonhoeffer, et al., Circulation 2000; 102: 813-816, the replacementpulmonary valve may be implanted to replace native pulmonary valves orprosthetic pulmonary valves located in valved conduits.

Various types and configurations of prosthetic heart valves are used inpercutaneous valve procedures to replace diseased natural human heartvalves. The actual shape and configuration of any particular prostheticheart valve is dependent to some extent upon the valve being replaced(i.e., mitral valve, tricuspid valve, aortic valve, or pulmonary valve).In general, the prosthetic heart valve designs attempt to replicate thefunction of the valve being replaced and thus will include valveleaflet-like structures used with either bioprostheses or mechanicalheart valve prostheses. In other words, the replacement valves mayinclude a valved vein segment that is mounted in some manner within anexpandable stent to make a stented valve. In order to prepare such avalve for percutaneous implantation, the stented valve can be initiallyprovided in an expanded or uncrimped condition, then crimped orcompressed around the balloon portion of a catheter until it is as closeto the diameter of the catheter as possible.

Other percutaneously-delivered prosthetic heart valves and systems fordelivering them have been suggested, such as by Bonhoeffer, P. et al.,“Transcatheter Implantation of a Bovine Valve in Pulmonary Position.”Circulation, 2002; 102:813-816, and by Cribier, A. et al. “PercutaneousTranscatheter Implantation of an Aortic Valve Prosthesis for CalcificAortic Stenosis.” Circulation, 2002; 106:3006-3008, the disclosures ofwhich are incorporated herein by reference. These heart valves anddelivery techniques rely at least partially upon a frictional type ofengagement between the expanded support structure and the native tissueto maintain a position of the delivered prosthesis, although the stentscan also become at least partially embedded in the surrounding tissue inresponse to the radial force provided by the stent and balloons that aresometimes used to expand the stent. Thus, with these transcathetertechniques, conventional sewing of the prosthetic heart valve to thepatient's native tissue is not necessary. Similarly, in an article byBonhoeffer, P. et al. titled “Percutaneous Insertion of the PulmonaryValve.” J Am Coll Cardiol, 2002; 39:1664-1669, the disclosure of whichis incorporated herein by reference, percutaneous delivery of abiological valve is described. The valve is sutured to an expandablestent within a previously implanted valved or non-valved conduit, or apreviously implanted valve. Again, radial expansion of the secondaryvalve stent is used for placing and maintaining the replacement valve.

Although there have been advances in percutaneous valve replacementtechniques and devices, there is a continued desire to provide differentdelivery systems for delivering cardiac valves to an implantation sitein a minimally invasive and percutaneous manner. There is also acontinued desire to be able to reposition and/or retract the valves oncethey have been deployed or partially deployed in order to ensure optimalplacement of the valves within the patient. In addition, there is adesire to provide a valve and corresponding delivery system that allowfor full or partial repositionability and/or retractability of the valveonce it is positioned in the patient.

SUMMARY

The delivery systems of the invention can be used to deliver replacementvalves to the heart of a patient. These replacement heart valves may beconfigured to provide complimentary features that promote optimalplacement of the replacement heart valve in a native heart valve, suchas the aortic valve, mitral valve, pulmonic valve, and/or tricuspidvalve. In some embodiments, the replacement heart valves of theinvention are highly amenable to transvascular delivery using anantegrade transapical approach (either with or without cardiopulmonarybypass and either with or without rapid pacing) or retrogradetransarterial approach (either with or without rapid pacing). Themethodology associated with the present invention can be repeatedmultiple times, such that several prosthetic heart valves of the presentinvention can be mounted on top of or within one another, if necessaryor desired.

The replacement heart valves each include a stent to which a valvestructure is attached. The stents of the invention include a widevariety of structures and features that can be used alone or incombination with features of other stents of the invention. Inparticular, these stents provide a number of different docking and/oranchoring structures that are conducive to percutaneous deliverythereof. Many of the structures are thus compressible to a relativelysmall diameter for percutaneous delivery to the heart of the patient,and then are expandable either via removal of external compressiveforces (e.g., self-expanding stents). The devices delivered by thedelivery systems described herein can be used to deliver stents, valvedstents, or other interventional devices such as ASD (atrial septaldefect) closure devices, VSD (ventricular septal defect) closuredevices, or PFO (patent foramen ovale) occluders.

Methods for insertion of the replacement heart valves of the inventioninclude delivery systems that can maintain the stent structures in theircompressed state during their insertion and allow or cause the stentstructures to expand once they are in their desired location. Inaddition, delivery methods of the invention can include features thatallow the stents to be retrieved for removal or relocation thereof afterthey have been deployed or partially deployed from the stent deliverysystems. The methods may include implantation of the stent structuresusing either an antegrade or retrograde approach. Further, in many ofthe delivery approaches of the invention, the stent structure isrotatable in vivo to allow the stent structure to be positioned in adesired orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further explained with reference to theappended Figures, wherein like structure is referred to by like numeralsthroughout the several views, and wherein:

FIG. 1 is a front view of one embodiment of a delivery system of theinvention;

FIG. 2 is a front view of another embodiment of a delivery system of theinvention with its sheath in a closed position;

FIG. 3 is a front view of the delivery system of FIG. 2, with its sheathpartially retracted to expose and partially expand a stent;

FIG. 4 is a front view of the delivery system of FIG. 3, with a distalend of the stent released from a distal tip of the delivery system;

FIG. 5 is a front view of the delivery system of FIG. 4 with its hookdriver in a stent-releasing position;

FIG. 6 is an enlarged front view of a portion of the delivery system andstent of FIG. 5;

FIG. 7 is a front view of the delivery system of FIG. 5, with the stentreleased or deployed from the delivery system;

FIG. 8 is an enlarged front view of a portion of the delivery system anddeployed stent of FIG. 7;

FIG. 9 is another front view of the delivery system of FIG. 7; and

FIG. 10 is a front view of the delivery system of FIG. 9, with thesheath positioned at the distal end of the system and enclosing the tipsof the wires that had been engaged with the stent.

DETAILED DESCRIPTION

As referred to herein, the prosthetic heart valves used in accordancewith the various devices and methods may include a wide variety ofdifferent configurations, such as a prosthetic heart valve that hastissue leaflets or a synthetic heart valve that has polymeric, metallic,or tissue-engineered leaflets. In this way, the heart valves can bespecifically configured for replacing any heart valve. That is, whilemuch of the description herein refers to replacement of aortic valves,the prosthetic heart valves of the invention can also generally be usedfor replacement of native mitral, pulmonic, or tricuspid valves, for useas a venous valve, or to replace a failed bioprosthesis, such as in thearea of an aortic valve or mitral valve, for example.

Although each of the valves used with the delivery devices and methodsdescribed herein would typically include leaflets attached within aninterior area of a stent, the leaflets are not shown in the illustratedembodiments for clarity purposes. In general, the stents describedherein include a support structure comprising a number of strut or wireportions arranged relative to each other to provide a desiredcompressibility and strength to the heart valve. Other details onparticular configurations of the stents of the invention are alsodescribed below; however, in general terms, stents of the invention aregenerally tubular support structures, and leaflets will be secured tothe support structure. The leaflets can be formed from a variety ofmaterials, such as autologous tissue, xenograph material, or syntheticsas are known in the art. The leaflets may be provided as a homogenous,biological valve structure, such as a porcine, bovine, or equine valve.Alternatively, the leaflets can be provided independent of one another(e.g., bovine or equine pericardial leaflets) and subsequently assembledto the support structure of the stent. In another alternative, the stentand leaflets can be fabricated at the same time, such as may beaccomplished using high strength nano-manufactured NiTi films producedat Advanced Bio Prosthetic Surfaces (ABPS) of San Antonio, Tex., forexample. The support structures are generally configured to accommodatethree leaflets; however, the replacement prosthetic heart valves canincorporate more or less than three leaflets.

In more general terms, the combination of a support structure with oneor more leaflets for a replacement heart valve that is delivered by thedelivery systems of the invention can assume a variety of otherconfigurations that differ from those shown and described, including anyknown prosthetic heart valve design. In certain embodiments of theinvention, the support structure with leaflets can be any knownexpandable prosthetic heart valve configuration, whether balloonexpandable, self-expanding, or unfurling (as described, for example, inU.S. Pat. Nos. 3,671,979; 4,056,854; 4,994,077; 5,332,402; 5,370,685;5,397,351; 5,554,185; 5,855,601; and 6,168,614; U.S. Patent ApplicationPublication No. 2004/0034411; Bonhoeffer P., et al., “PercutaneousInsertion of the Pulmonary Valve”, Pediatric Cardiology, 2002;39:1664-1669; Anderson H R, et al., “Transluminal Implantation ofArtificial Heart Valves”, EUR Heart J., 1992; 13:704-708; Anderson, J.R., et al., “Transluminal Catheter Implantation of New ExpandableArtificial Cardiac Valve”, EUR Heart J., 1990, 11: (Suppl) 224a; HilbertS. L., “Evaluation of Explanted Polyurethane Trileaflet Cardiac ValveProsthesis”, J Thorac Cardiovascular Surgery, 1989; 94:419-29; Block PC, “Clinical and Hemodyamic Follow-Up After Percutaneous AorticValvuloplasty in the Elderly”, The American Journal of Cardiology, Vol.62, Oct. 1, 1998; Boudjemline, Y., “Steps Toward Percutaneous AorticValve Replacement”, Circulation, 2002; 105:775-558; Bonhoeffer, P.,“Transcatheter Implantation of a Bovine Valve in Pulmonary Position, aLamb Study”, Circulation, 2000:102:813-816; Boudjemline, Y.,“Percutaneous Implantation of a Valve in the Descending Aorta In Lambs”,EUR Heart J, 2002; 23:1045-1049; Kulkinski, D., “Future Horizons inSurgical Aortic Valve Replacement: Lessons Learned During the EarlyStages of Developing a Transluminal Implantation Technique”, ASAIO J,2004; 50:364-68; the teachings of which are all incorporated herein byreference).

Orientation and positioning of the stents of the invention may beaccomplished either by self-orientation of the stents (such as byinterference between features of the stent and a previously implantedstent or valve structure) or by manual orientation of the stent to alignits features with anatomical or previous bioprosthetic features, such ascan be accomplished using fluoroscopic visualization techniques, forexample. For example, when aligning the stents of the invention withnative anatomical structures, they should be aligned so as to not blockthe coronary arteries, and native mitral or tricuspid valves should bealigned relative to the anterior leaflet and/or thetrigones/commissures.

Some embodiments of the support structures of the stents describedherein can be a series of wires or wire segments arranged so that theyare capable of transitioning from a collapsed state to an expandedstate. The stents may further include a number of individual wiresformed of a metal or other material. These wires are arranged in such away that a support structure allows for folding or compressing to acontracted state in which its internal diameter is greatly reduced fromits internal diameter in an expanded state. The delivery systems usedfor such a stent should be provided with degrees of rotational and axialorientation capabilities in order to properly position the new stent atits desired location.

The wires of the support structure of the stents can be formed from ashape memory material such as a nickel titanium alloy (e.g., Nitinol).With this material, the support structure is self-expandable from acontracted state to an expanded state, such as by the application ofheat, energy, and the like, or by the removal of external forces (e.g.,compressive forces). This support structure can also be repeatedlycompressed and re-expanded multiple times without damaging the structureof the stent. In addition, the support structure of such an embodimentmay be laser cut from a single piece of material or may be assembledfrom a number of different components. For these types of stentstructures, one example of a delivery system that can be used includes acatheter with a retractable sheath that covers the stent until it is tobe deployed, at which point the sheath can be retracted to allow thestent to expand. Further details of such embodiments are discussedbelow.

Referring now to the Figures, wherein the components are labeled withlike numerals throughout the several Figures, and initially to FIG. 1,one embodiment of a stent delivery system 10 is illustrated. This system10 includes a proximal end 12 and a distal end 14. Proximal end 12includes a tip knob 16, a hook driver 18, and a stop 20, all of whichare used in controlling the delivery and deployment of a stent 30 at thegenerally distal end 14 of the delivery system 10. The distal end 14 ofthe delivery system 10 includes a tip 22, which is shown adjacent to thestent 30. The delivery system further includes a threaded rod 24 and asheath 26. The sheath 26 generally includes an elongated tubular portion28 that has a hollow interior portion with a first diameter that issized for compression and retention of the stent 30 within its interiorarea prior to deployment of the stent 30. The sheath 26 further includesa handle portion 32 that is proximal to the elongated portion 28. Thehandle portion 32 is designed to be held and manipulated by the user forcontrolling the longitudinal movement of the sheath 26. The handleportion 32 further includes an internal threaded mechanism that engageswith the threaded rod 24 to provide incremental linear movement of thesheath 26 along the length of the delivery system 10. That is, thesheath 26 is moveable toward either the proximal end 12 or distal end 14by rotating the handle portion 32 about the longitudinal axis of thedelivery system, thereby moving the inner threaded mechanism along thehelical screw of the threaded rod 24. The sheath 26 may or may notrotate with the handle portion 32. The handle portion 32 furtherincludes a push-button 34 that releases the inner threaded portion ofthe sheath from its engagement with the threaded rod 24 so that thesheath 26 can slide relatively freely along the length of the threadedrod 24. Thus, the sheath 26 also has the capability of being quicklyadvanced or retracted when its inner threaded mechanism is released fromthe threaded rod 24, while also having the capability of being advancedand retracted more slowly and accurately by rotating the handle portion32 along the threaded rod 24.

The exemplary stent 30 is made of a series of wires that arecompressible and expandable through the application and removal ofexternal forces, and may include a series of Nitinol wires that areapproximately 0.010-0.015 inches in cross-section. That is, the stent 30in this embodiment is a self-expanding stent. As shown in FIG. 1, thestent 30 is captured at a first end 36 by the tip 22 and is captured ata second end 38 by the sheath 26. This configuration of the deliverysystem 10 enables independent release of the first and second ends 36,38 of the stent of the stent 30 from the system. In this way, both endsof the stent 30 can be controlled during the deployment thereof to besure that it is properly positioned within the target anatomy prior tofully releasing the stent 30 from the delivery system 10. The mechanicalstop 20 is located at the proximal end of the threaded rod 24 to controlthe distance that the sheath 26 can be moved toward the proximal end 12during the process of unsheathing the stent 30.

Another exemplary delivery system 100 and process of deploying a stent130 is illustrated in FIGS. 2-10. This method can be used for apicaldelivery of a stent to an aorta, or it can be used for other deliveryapproaches, such as for transarterial retrograde delivery. The deliverysystem 100 provides the capability for loading of a stent 130 onto thesystem, at least partially deploying the stent, then retracting thestent back into the delivery system and relocating it, if desired.

In particular, FIG. 2 illustrates a delivery system 100 including adistal tip 122 adjacent to a sheath 126 in which a stent is enclosed.The stent 130 of this embodiment is illustrated as being engaged withmultiple wires or elements having angled end portions or protrusions,although it is understood that the stent could be attached to thedelivery system using an alternate attachment configuration. In theembodiment of FIG. 2 and as is more clearly shown in the enlarged viewof FIG. 6, the delivery system includes multiple elements 150 extendingfrom the distal end of the sheath 126. The number of elements 150 ispreferably the same as the number of crowns at a proximal end 136 of thestent 130, although the number of elements 150 can be different from thenumber of crowns. Each of the elements 150 includes an angled wire tipor protrusion 152 that extends at an angle from its respective element150. The angle between the protrusion or tip 152 and its respectiveelement 150 can be approximately 90 degrees, although it can be anyangle that provides for secure engagement between the elements 150 andthe stent 130 in the manner described below. Alternatively, a suture orwire without an angled tip or protrusion 152 could be used to securelyengage the stent to the delivery system 100, or an attachment end couldcontain multiple protrusions that fit to the stent. In anotheralternative, the stent itself can include a structure for engagementwith a delivery system. In any case, it is important that the geometryof the stent and/or any type of stent engaging elements provide for bothsecure capture of the stent and easy stent release from the deliverysystem, when desired.

Referring specifically to FIG. 6, the elements 150 with an angled wiretip or protrusion 152 are shown in an enlarged view. In thisconfiguration, a sleeve 170 is positioned over the relatively straightportion of wire or element 150, but retracted relative to its angledwire tip 152. When the element 150 is engaged with the stent crown, thesleeve 170 can be slid toward the stent crown until it encases both theend of the stent crown and the angled wire tip or protrusion 152,thereby providing a more secure attachment of the components relative toeach other. The sleeve 170 is preferably made of a relatively flexiblematerial that can deform and expand as it slides over the stent crownand angled wire tip 152. This sleeve 170 helps to prevent disengagementof each angled wire tip 152 from its respective stent crown.

The delivery system 100 further includes driver mechanisms at itsproximal end 112, including a sheath push-button 134, a counter-rotationknob 140, a hook driver 142, and a tip thumb knob 116. A threaded rod124 is positioned between the counter-rotation knob 140 and the sheathpush-button 134 when the delivery system is at this step of the process.The delivery system 100 can then be used to position the stent 130 inits target location in the patient.

For an antegrade approach (e.g., a transapical approach), once thedelivery system 100 has been located within the patient so that thestent and/or valve is in its desired position, such as within the aorticvalve, the sheath 126 is pulled back toward the proximal end 112 of thedelivery system, as shown in FIG. 3, until it exposes the inflow(proximal) end of the stent 130. This removal of the compressive forceprovided by the sheath allows the stent 130 to then expand radially.Alternatively, in a transarterial retrograde delivery approach, theinflow or distal end of the stent 130 can remain compressed while themiddle, or middle and proximal end, of the stent, along with otherfeatures such as petals, for example, are radially expanded. Any minorpositional adjustments, if necessary, can be made at this point.However, if it is determined that the stent 130 is far enough from thedesired position that major repositioning is necessary, the sheath 126can be moved back toward the distal end 114 of the delivery system 100until the entire stent 130 is again enclosed within the sheath 126. Thedelivery system 100 can then be repositioned until it is in its desiredlocation. The delivery system 100 may also include a stop on its handleor some other portion of its structure that requires a positive actionby the user to prevent inadvertent release of the stent 130 from thedelivery system 100.

FIG. 4 illustrates the step of deploying the outflow (distal) end of thestent 130. In this step, the tip thumb knob 116 near the proximal end112 is pressed to deploy the outflow end of the stent 130 so that it isfree from the distal tip portion 122. When using an alternativetransarterial retrograde approach, this mechanism can instead be used toradially expand the inflow end of the stent 130 after the middle portionof the stent 130, along with any other features provided on the stentsuch as petals, are radially expanded.

As shown in FIGS. 5 and 6, the hook driver 142 can be translateddistally to release the stent 130 from the sleeves 170 that covered theangled wire tips 152 and their corresponding stent crowns. This isaccomplished by driving the hooks or angled wire tips 152 forward. Thesheath 126 is then driven toward the stent 130 to move the wire tips 152toward the central axis of the delivery system 100 and toward thecentral axis of the stent 130, thereby allowing the inflow (proximal)end of the stent 130 to fully release from delivery system 100, as shownin FIGS. 7-9.

In an alternative embodiment, in order to deploy a stent when it isproperly positioned in a lumen of the patient, the sheath can be pulledback to expose the stent and the wires engaged with the crowns of thestent. The stent can be released by pulling the wires back toward thecentral axis of the device to disengage them from the stent crowns. Theprocess of pulling the wires toward the central axis can be accomplishedin a number of ways, such as by rotating the sheath over coarse threadsor pushing a sheath push-button to slide it to pull the wires toward thecentral axis and away from the stent. However, a number of differentmechanisms can be used to accomplish this movement of the wires relativeto the stent crowns. One example of an alternative mechanism forreleasing the stent from the delivery system is to pull sleeves backfrom their respective angled wire tips or protrusions.

The hook driver 142 is then translated proximally to pull the angledwire tips 152 of the wires 150 into the same sleeves 170 that are alsoused to secure the angled wire tips 152 to the stent crowns. In thisway, the angled wire tips 152 are protected from getting caught on thesheath 126 when the sheath 126 is driven toward the outflow end of thedelivery system 100 to cover or “re-sheath” the wires 150 prior toremoving the system 100 from the patient, as shown in FIG. 10. If thestent 130 includes crowns that are not all generally in the same plane(e.g., some crowns are further from one of the ends of the stent thanother crowns), the delivery system 100 may include wires that havedifferent lengths in order to capture all of the stent crowns. Thus, thedelivery system provides both the function of withdrawing the sheath 126and withdrawing the sleeves 170, when desired in the stent deliveryprocess.

It is noted that in the above procedure, the stent can be retracted backinto the sheath at any point in the process until the wires aredisengaged from the stent. This may be useful for repositioning of thestent if it is determined that the stent has been improperly positionedrelative to the patient's anatomy. In this case, the steps describedabove can be repeated until the desired positioning of the stent in thepatient's anatomy is achieved.

With this system described above, full or partial blood flow through thevalve can advantageously be maintained during the period when thestented valve is being deployed into the patient but is not yet releasedfrom its delivery system. This feature can help to prevent complicationsthat may occur when blood flow is stopped or blocked during valveimplantation with some other known delivery systems. In addition, it ispossible for the clinician to thereby evaluate the opening and closingof leaflets, examine for any paravalvular leakage and evaluate coronaryflow and proper positioning of the valve within the target anatomybefore final release of the stented valve.

The delivery systems described above can be modified to additionally oralternatively deliver a balloon-expandable stent to the target site ofthe patient. Delivering balloon-expandable stents to the implantationlocation can be performed percutaneously. In general terms, thisincludes providing a transcatheter assembly, including a deliverycatheter, a balloon catheter, and a guide wire. Some delivery cathetersof this type are known in the art, and define a lumen within which theballoon catheter is received. The balloon catheter, in turn, defines alumen within which the guide wire is slideably disposed. Further, theballoon catheter includes a balloon that is fluidly connected to aninflation source. For a balloon-expandable stent, the transcatheterassembly is appropriately sized for a desired percutaneous approach tothe implantation location. For example, the transcatheter assembly canbe sized for delivery to the heart valve via an opening at a carotidartery, a jugular vein, a sub-clavian artery or vein, femoral artery orvein, or the like. Essentially, any percutaneous intercostal or vascularpenetration can be made to facilitate use of the transcatheter assembly.

Prior to delivery, the stent is mounted over the balloon in a contractedstate to be as small as possible without causing permanent deformationof the stent structure. As compared to the expanded state, the supportstructure is compressed onto itself and the balloon, thus defining adecreased inner diameter as compared to an inner diameter in theexpanded state. While this description is related to the delivery of aballoon-expandable stent, the same basic procedures can also beapplicable to a self-expanding stent, where the delivery system wouldnot include a balloon, but would preferably include a sheath or someother type of configuration for maintaining the stent in a compressedcondition until its deployment.

With the stent mounted to the balloon, the transcatheter assembly isdelivered through a percutaneous opening (not shown) in the patient viathe delivery catheter. The implantation location is located by insertingthe guide wire into the patient, which guide wire extends from a distalend of the delivery catheter, with the balloon catheter otherwiseretracted within the delivery catheter. The balloon catheter is thenadvanced distally from the delivery catheter along the guide wire, withthe balloon and stent positioned relative to the implantation location.In an alternative embodiment, the stent is delivered to an implantationlocation via a minimally invasive surgical incision (i.e.,non-percutaneously). In another alternative embodiment, the stent isdelivered via open heart/chest surgery. In one embodiment of the stentsof the invention, the stent includes a radiopaque, echogenic, or Millvisible material to facilitate visual confirmation of proper placementof the stent. Alternatively, other known surgical visual aids can beincorporated into the stent. The techniques described relative toplacement of the stent within the heart can be used both to monitor andcorrect the placement of the stent in a longitudinal direction relativeto the length of the anatomical structure in which it is positioned.

Once the stent is properly positioned, the balloon catheter is operatedto inflate the balloon, thus transitioning the stent to an expandedstate. Alternatively, where the support structure is formed of a shapememory material, the stent can self-expand to its expanded state.

One or more markers on the valve, along with a corresponding imagingsystem (e.g., echo, MRI, etc.) can be used with the variousrepositionable delivery systems described herein in order to verify theproper placement of the valve prior to releasing it from the deliverysystem. A number of factors can be considered, alone or in combination,to verify that the valve is properly placed in an implantation site,where some exemplary factors are as follows: (1) lack of paravalvularleakage around the replacement valve, which can be advantageouslyexamined while blood is flowing through the valve since these deliverysystems allow for flow through and around the valve; (2) optimalrotational orientation of the replacement valve relative to the coronaryarteries; (3) the presence of coronary flow with the replacement valvein place; (4) correct longitudinal alignment of the replacement valveannulus with respect to the native patient anatomy; (5) verificationthat the position of the sinus region of the replacement valve does notinterfere with native coronary flow; (6) verification that the sealingskirt is aligned with anatomical features to minimize paravalvularleakage; (7) verification that the replacement valve does not inducearrhythmias prior to final release; and (8) verification that thereplacement valve does not interfere with function of an adjacent valve,such as the mitral valve.

The present invention has now been described with reference to severalembodiments thereof. The foregoing detailed description and exampleshave been given for clarity of understanding only. No unnecessarylimitations are to be understood therefrom. It will be apparent to thoseskilled in the art that many changes can be made in the embodimentsdescribed without departing from the scope of the invention. Thus, thescope of the present invention should not be limited to the structuresdescribed herein.

1-20. (canceled)
 21. A delivery system for delivering an implantablestented device to a lumen of a patient, the delivery system comprising:an elongated body comprising a proximal end and a distal end comprisinga tip; a plurality of stent engagement elements, wherein each stentengagement element includes an elongated wire and a tip portion forengagement with the implantable stented device; a plurality of sleeves,wherein each sleeve surrounds a respective stent engagement element,wherein the plurality of sleeves and stent engagement elements include afirst position wherein each sleeve surrounds a respective one of the tipportions and a portion of the implantable stented device and a secondposition wherein each sleeve is spaced proximally of the respective tipportion; a sheath comprising an elongated tubular portion having ahollow interior portion with a first diameter that is sized forcompression and retention of the implantable stented device in acompressed configuration for delivery to a body lumen, wherein with thestent engagement elements and the sleeves in the second position, thesheath is configured such that advancement of the sheath distally causesthe tip portions to move towards a central longitudinal axis of thedelivery system to disengage the tip portions from the implantablestented device.
 22. The delivery system of claim 21, wherein the tipportion of each of the plurality of stent engagement elements comprisesan angled wire tip.
 23. The delivery system of claim 21, wherein the tipof the distal end of the elongated body includes a hollow interiorportion for compression and retention of a distal end of the implantablestented device.
 24. The delivery system of claim 23, further comprisinga tip controller at the proximal end of the elongated body, wherein thetip controller is coupled to the tip to move the tip relative to thesheath for deployment of the distal end of the implantable stenteddevice.
 25. The delivery system of claim 21, further comprising a stopmechanism at the proximal end of the elongated body for controllingaxial movement of the sheath in a proximal direction relative to theelongated body.
 26. The delivery system of claim 21 in combination witha self-expanding stented device.
 27. The combination of claim 26,wherein the stented device comprises a central lumen and a valvepositioned within the central lumen.
 28. The combination of claim 26,wherein the stented device comprises a replacement prosthetic heartvalve.
 29. A delivery system for delivering an implantable stenteddevice to a lumen of a patient, the delivery system comprising: anelongated body comprising a proximal end and a distal end comprising atip; a sheath comprising an elongated tubular portion having a hollowinterior portion that is sized for compression and retention of theimplantable stented device in a compressed configuration for delivery toa body lumen; a plurality of stent engagement mechanisms, each of theplurality of stent engagement mechanisms being axially translatable froma distal end of the sheath and each of which includes a first portionand a second portion engageable with a proximal end of a stented device;and a plurality of sleeves surrounding the stent engagement mechanisms;wherein the plurality of sleeves are movable between a stent engagementposition wherein each sleeve surrounds the second portion of arespective one of the stent engagement mechanisms and a portion of theimplantable stent device, and a stent deployment position wherein thesecond portion of each stent engagement mechanism is spaced axiallydistal of each respective sleeve, wherein with the stent engagementmechanisms in the stent deployment position, movement of the sheathdistally causes the stent engagement mechanisms to move toward a centralaxis of the elongated body such that the second portions of the stentengagement mechanisms disengage from the implantable stented device. 30.The delivery system of claim 29, wherein the second portion of each ofthe stent engagement mechanisms is angled with respect to the firstportion of the respective stent engagement mechanism.
 31. The deliverysystem of claim 30, wherein the second portion of each of the stentengagement mechanisms extends at an approximately 90 degree angle fromthe first portion of its respective stent engagement mechanism.